Description:Species Description - Filaments erect for the most part, more or less fasciculate, sparsely branched, about 1 mm. long, 10-13 µ diam.; trichomes clavate at the outer apical end, 3-5 µ diam. in the older parts, 6-9 µ diam. at the apices; cells up to 24 µ long, cylindrical or slightly dolioform in the middle and older parts, decidedly dolioform at the apices in some of the younger filaments, pale aeruginous, homogeneous; cross-walls very inconspicuous; heterocysts of the same size and shape as the cells; sheath relatively thick, subgelatinous, homogeneous, hyaline; branching mostly single but some geminate.

Distribution and Ecology - Growing on rocks by a water reservoir in Eio Piedras, no. 108, type; on rocks at the Experiment Station, Rio Piedras, no. 174; on rocks by the road to Monte Montoro, Mariacao, no. 1066; north of Maricao, no. 1246.